ATM exchange

ABSTRACT

A temporarily saved band value management table for managing temporarily saved band value is provided, as is a band management table for managing empty band value in the storage device of an ATM exchange comprising a storage device, a control device, and the like. The control device selects a corresponding empty band value for a temporarily saved band value when a first camp-on request is received from a terminal, and sets the empty band value to “0.” In addition, the control device adds to the temporarily saved band value a band value released by a break in communication when a camp-on request is registered, and grants permission for communication to the terminal that has issued this camp-on request when the temporarily saved band value is higher than the band value required by a registered camp-on request. The control device determines whether or not a connection request can be accepted on the basis of the empty band value stored in the band management table.

This is a continuation, of application Ser. No. 08/619,404, filed Mar.21, 1996 now U.S. Pat. No. 5,812,551.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ATM exchange used in an ATMcommunications system, and more particularly to an ATM exchange capableof performing camp-on registration.

2. Description of the Related Art

An ATM (Asynchronous Transfer Mode) communications system comprises anetwork in which a plurality of ATM exchanges are connected bytransmission lines, and terminals connected to each ATM exchange.

In a common ATM communications system, a terminal notifies an ATMexchange of the desired band, quality, and other connection requirementswhen a call connection is requested. The ATM exchange investigateswhether or not sources that satisfy these connection requirements can befound, performs the call connection when this can be offered, andnotifies this terminal that the connection is denied when this cannot beoffered. A terminal whose call request has been accepted performscommunication, whereas a terminal that has been notified of a connectionrefusal repeats its requests for a call connection until it is accepted.

There are also ATM communications systems that use ATM exchanges capableof camp-on request registration. In such ATM communications systems, aterminal that has been notified of a connection refusal can issue acamp-on request, and the ATM exchange that has received the camp-onrequest monitors an empty band value and grants permission tocommunicate to the terminal that has issued the camp-on registrationwhen the empty band value exceeds the band value required for thecamp-on request.

The structure and operation of a conventional ATM exchange capable ofperforming camp-on registration will now be described in further detailwith reference to FIG. 50.

As shown in the figure, a conventional ATM exchange 100 comprises asubscriber's line circuit 30, a switching unit 20, an output buffer 40,a control device 200, and a storage device 300 as its main constituentelements. The subscriber's line circuit 30 is a circuit for providing aninterface with terminals T1 through Tn; the switching unit 20 identifiesthe addresses from the headers of the cells (fixed-length data thatconstitute a portion of the communications content) that have beeninputted via the subscriber's line circuit 30, and presents the addressto the output buffer 40. The output buffer 40 temporarily accumulatesthe cells and sends them out over a transmission line 50.

The control device 200 monitors the operating condition (empty bandvalue #0) of the transmission line 50 and changes the empty band value#0 in accordance with the used or released band value when a callconnection or disconnection occurs. The empty band value #0 and therequired band value are compared with each other and connection receiptmanagement is performed when a call connection has been requested. Forexample, the requested call is connected and the empty band value #0 isreduced by #Ti when a call connection requiring a band value #Ti (<#0)has been made from a terminal Ti. Meanwhile, a terminal Tj is notifiedof a refusal to connect when a call connection requiring a band value#Tj (>#0) has been made from the terminal Tj.

In addition, when a camp-on request have been issued from a terminal,the control device 200 registers the content thereof in the storagedevice 300. Every time a band value is released due to disruptedcommunication, it is determined whether or not the empty band value #0exceeds the band value required for the registered camp-on request, anda call that corresponds to this camp-on request is established on thetransmission line 50 when the empty band value #0 has exceeded therequired band value.

As described above, in a conventional ATM exchange it is determinedwhether or not a connection request has been received based on the emptyband value #0. The determination as to whether or not permission hasbeen granted with respect to a camp-on request is also performed basedon the empty band value #0. In a conventional ATM exchange, therefore,when a request is received for a call connection that uses a band belowthe empty band value after a camp-on request has been registered, a longtime is often needed to finally establish a call in accordance with thisconnection request. For example, a long time is often needed before acamp-on request that requires a substantial band value is executed, aswhen television images are transmitted.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an ATM exchange inwhich a permission for a camp-on request is issued in a short time.

The first ATM exchange pertaining to the present invention receives fromterminals call connection requests and camp-on requests in which theband values being used are specified, and establishes on a transmissionline calls for which the specified band values can be used, wherein thisATM exchange comprises a band value storage unit, a camp-on requeststorage unit, a connection request response unit, a camp-on requestregistration unit, a band value setting unit, a band value updatingunit, a camp-on request response unit, and a post-processing unit.

The band value storage unit divides the unused band value of thetransmission line into a empty band value and temporarily saved bandvalue, and stores them. The camp-on request storage unit stores thecontents of camp-on requests issued by each terminal, in correlationwith the processing rank of these contents.

The connection request response unit establishes on the transmissionline the call requested by a connection request when the connectionrequest received from a terminal is one for which the use of a bandvalue below the empty band value stored in the band value storage unithas been specified, and notifies the terminal of a refusal to connectwhen the connection request is such that the use of a band valueexceeding the empty band value has been specified. In addition, thecamp-on request registration unit, upon receipt of a camp-on requestfrom a terminal, establishes the processing rank of this camp-on requestand performs registration in the camp-on request storage unit incorrelation with the processing rank that identifies the camp-on requestdata that represent the contents of this camp-on request. The band valuesetting unit adds the empty band value stored in the band value storageunit to the temporarily saved band values stored in the band valuestorage unit, and setting zero for the empty band value in the bandvalue storage unit, when the registration of camp-on request data by thecamp-on request registration unit is performed with respect to a camp-onrequest storage unit in which no camp-on request data have beenregistered.

The band value updating unit adds a band value released by adisconnected call to a temporarily saved band value stored in the bandvalue storage unit when camp-on request data have been registered in thecamp-on request storage unit upon detection of the disconnected call inthe transmission line. In addition, the band value updating unit adds aband value released by a disconnected call to an empty band value storedin the band value storage unit when no camp-on request data have beenregistered in the camp-on request storage unit upon detection of adisconnected call in the transmission line.

The camp-on request response unit establishes a call that corresponds tocamp-on request data in the transmission line when the temporarily savedband value stored in the band value storage unit exceeds the band valuespecified for use by the camp-on request data that are stored in thecamp-on request storage unit and that are assigned the highestprocessing rank. The post-processing unit reduces the temporarily savedband value stored in the band value storage unit by the band value usedto set up a call when it is set up by the camp-on request response unit,and erases the camp-on request data that is stored in the camp-onrequest storage unit and that have been used by the camp-on requestresponse unit.

Specifically, in the first ATM exchange of the present invention, bandvalue not used for communication are monitored and divided into theempty band value used to determine whether or not a connection requesthas been received, and the temporarily saved band value used todetermine whether or not there has been a response to a camp-on request,and the band values that have been released following receipt of acamp-on request are all used for camp-on requests. A terminal connectedto the first ATM exchange can therefore start communication soon after acamp-on request has been issued.

The camp-on request registration unit adopted for use in the first ATMexchange of the present invention may be a unit for assigning to camp-onrequest data a processing rank indicating that a processing sequence isto be conducted following the processing of the camp-on request dataregistered in the camp-on request data storage unit when the camp-onrequest data are registered for a newly received camp-on request.

In addition, a second ATM exchange can be obtained by further providingthe first ATM exchange with a class storage unit for storing classesassigned to different terminals. The addition of a class storage unit,however, leads to the use of a camp-on request registration unit forchanging the processing rank of each piece of the camp-on request datain the camp-on request storage unit in such a way that the camp-onrequest data are processed in accordance with a sequence thatcorresponds to the classes assigned to terminals and stored in the classstorage unit when camp-on request data concerning camp-on requests newlyreceived from the terminals are registered in the camp-on requeststorage unit.

Setting up a communications system in which a second ATM exchange thusconfigured is used allows camp-on requests to be processed in accordancewith the priority ranks that correspond to the classes of terminals,making it possible to conduct effective communication.

It is also possible to further provide the first ATM exchange of thepresent invention with a time-specific class storage unit for storingclasses related to different terminals for each time period, and toadopt as a camp-on request registration unit a unit for changing theprocessing rank of each piece of the camp-on request data in the camp-onrequest storage unit in such a way that the camp-on request data areprocessed in accordance with a sequence that corresponds to the classesassigned to terminals at the present moment and stored in the classstorage unit when camp-on request data concerning camp-on requests newlyreceived from the terminals are registered in the camp-on requeststorage unit.

The second ATM exchange of the present invention can be further providedwith a second class storage unit for storing a second type of class dataand waiting time data concerning each terminal; a selection unit forselecting, from among the camp-on request data stored in the camp-onrequest storage unit, camp-on request data in which the time that haselapsed following registration exceeds the waiting time data stored inthe second class storage unit for a terminal that has issued a camp-onrequest; and a second processing rank change unit for changing theprocessing rank of each peace of the camp-on request data stored in thecamp-on request storage unit in such a way that the camp-on request dataselected by the selection unit are processed in accordance with an orderthat corresponds to the second class stored in the second class storageunit for the terminal that has issued this camp-on request.

An allocated band value storage unit for storing interrelations betweenterminals and allocated band values can also be added to the first ATMexchange of the present invention. The connection request response unitused in this case may be a unit for issuing a refusal to connect when aband value is higher than the allocated band value stored in theallocated band value storage unit for a terminal, even in cases in whicha connection request that requires the use of a band value below theempty band value in the band value storage unit has been received fromthe terminal. In addition, the camp-on request registration unit usedmay be a unit for issuing a refusal to register a camp-on request from aterminal when the band value specified for use with the camp-on requestreceived from the terminal is higher than the allocated band valuestored in the allocated band value storage unit for this terminal.

The second ATM exchange of the present invention can be further providedwith a class-specific allocated band value storage unit fir storinginterrelations between classes and allocated band values. The connectionrequest response unit used in this case may be a unit for issuing arefusal to connect when a band value is higher than the allocated bandvalue stored in the class-specific allocated band value storage unit forthe class of a terminal, even in cases in which a connection requestthat requires the use of a band value below the empty band value in theband value storage unit has been received from the terminal. Inaddition, the camp-on request registration unit used may be a unit forissuing a refusal to register a camp-on request from a terminal when theband value specified for use with the camp-on request received from theterminal is higher than the allocated band value stored in theclass-specific allocated band value storage unit for this terminal.

A secured empty band value storage unit for storing interrelationsbetween terminals and secured empty band values can also be added to thefirst ATM exchange of the present invention. The connection requestresponse unit used in this case may be a unit for establishing arequested call on the transmission line only in those cases in which thevalue stored in the band value storage unit when a call connection hasbeen requested by a terminal is the empty band value that exceed thevalue obtained by adding the requested band value and the secured emptyband value stored in the secured empty band value unit for thisterminal. In addition, the camp-on request registration unit used is aunit for adding the secured empty band value stored in the secured emptyband value unit for the terminal that has issued a camp-on request tothe temporarily saved band value in the band value storage unit, and forsubtracting this secured empty band value from the empty band value inthe band value storage unit, when a camp-on request has been received inthe absence of an object of monitoring (camp-on request).

A class-specific secured empty band value storage unit for storinginterrelations between classes and secured empty band values can also beadded to the second ATM exchange of the present invention. Theconnection request response unit used in this case may be a unit forestablishing the requested call on a transmission line only in thosecases in which the value stored in the band value storage unit when acall connection has been requested by a terminal is the empty bandvalues that exceed the values obtained by adding the requested bandvalue and the secured empty band value stored in the class-specificsecured empty band value unit for this terminal. In addition, thecamp-on request registration unit used is a unit for adding the securedempty band value stored in the class-specific secured empty band valueunit for the terminal that has issued a camp-on request to thetemporarily saved band value in the band value storage unit, and forsubtracting this secured empty band value from the empty band value inthe band value storage unit, when a camp-on request is received in theabsence of a monitoring object.

A caller-specific class storage unit for storing the interrelationsbetween classes and caller identification information can also be addedto the first ATM exchange of the present invention. The unit used as thecamp-on request registration unit in this case is a unit for changingthe processing rank of each peace of the camp-on request data in thecamp-on request storage unit in such a way that the received camp-onrequest is processed in accordance with a sequence that corresponds tothe class stored in the caller-specific class storage unit incorrelation with the identification information contained in thiscamp-on request.

In addition, the unit used as the connection request response unitshould be a unit for providing information about the number of pieces ofthe camp-on request data registered in the camp-on request storage unitwhen a terminal has been given a message that a connection has beenrefused.

A third ATM exchange of the present invention receivesterminal-originated requests for call connections for which the bandvalue to be used are specified, and establishes a call in which thespecified band value can be utilized in a transmission line, whereinthis ATM exchange comprises a band value storage unit, a camp-on requeststorage unit, a connection request processing unit, a band value settingunit, a band value updating unit, a camp-on request response unit, and apost-processing unit.

The band value storage unit is used to divide the unused band value of atransmission line into an empty band value and a temporarily saved bandvalues, and to store them. The camp-on request storage unit is used tostore the contents of camp-on requests in correlation with theprocessing ranks thereof.

The connection request processing unit establishes on a transmissionline a call requested by a connection request when the connectionrequest received from a terminal is one for which the use of a bandvalue below the empty band value stored in the band value storage unithas been specified. In addition, the connection request processing unitconsiders a connection request to be a camp-on request when theprocessing rank received from a terminal is one for which the use of aband value above the empty band value stored in the band value storageunit has been specified, establishes the processing rank of this camp-onrequest, and performs registration in the camp-on request storage unitin correlation with the processing rank that identifies the camp-onrequest data that represent the contents of this camp-on request.

The band value setting unit adds the empty band value stored in the bandvalue storage unit to the temporarily saved band value stored in theband value storage unit, and setting zero for the empty band values inthe band value storage unit, when the registration of camp-on requestdata by the camp-on request processing unit is performed with respect toa camp-on request storage unit in which no camp-on request data havebeen registered.

The band value updating unit adds a band value released by adisconnected call to a temporarily saved band value stored in the bandvalue storage unit when camp-on request data have been registered in thecamp-on request storage unit upon detection of a disconnected call inthe transmission-line. In addition, the band value updating unit adds aband value released by a disconnected call to an empty band value storedin the band value storage unit when no camp-on request data have beenregistered in the camp-on request storage unit upon detection of adisconnected call in the transmission line.

The camp-on request response unit establishes a call that corresponds tocamp-on request data-in the transmission line when the temporarily savedband value stored in the band value storage unit exceeds the band valuespecified for use by the camp-on request data that are stored in thecamp-on request storage unit and that are assigned the highestprocessing rank. The post-processing unit reduces the temporarily savedband value stored in the band value storage unit by the band value usedto set up a call when it is set up by the camp-on request response unit,and erases the camp-on request data that is stored in the camp-onrequest storage unit and that have been used by the camp-on requestresponse unit.

Specifically, when a connection request cannot be received, the thirdATM exchange considers this connection request to be a camp-on requestand registers it.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram depicting the structure of an ATM exchangepertaining to a first embodiment of the present invention;

FIG. 2 is a diagram depicting an example of a communications systemformed by the ATM exchanges of the present invention;

FIG. 3 is a block diagram depicting a call management table accommodatedin the ATM exchange of the first embodiment;

FIG. 4 is a block diagram of a band management table accommodated in theATM exchange of the first embodiment;

FIG. 5 is a block diagram of a routing table accommodated in the ATMexchange of the first embodiment;

FIG. 6 is a schematic illustrating a connection request acceptanceprocess performed by the ATM exchange of the first embodiment;

FIG. 7 is a block diagram of a camp-on request management tableaccommodated in the ATM exchange of the first embodiment;

FIG. 8 is a block diagram of a temporarily saved band value managementtable accommodated in the ATM exchange of the first embodiment;

FIG. 9 is a flow chart depicting a camp-on request registrationprocedure performed by the ATM exchange of the first embodiment;

FIG. 10 is a flow chart depicting a band value updating procedureperformed by the ATM exchange of the first embodiment;

FIG. 11 is a sequence diagram for terminals and the ATM exchange of thefirst embodiment;

FIG. 12 is a block diagram depicting the structure of the ATM exchangepertaining to a second embodiment of the present invention;

FIG. 13 is a block diagram of a terminal-specific class tableaccommodated in the ATM exchange of the second embodiment;

FIG. 14 is a flow chart depicting a camp-on request registrationprocedure performed by the ATM exchange of the second embodiment;

FIG. 15 is a sequence diagram for terminals and the ATM exchange of thesecond embodiment;

FIG. 16 is a block diagram depicting the structure of the ATM exchangepertaining to a third embodiment of the present invention;

FIG. 17 is a block diagram of a class change condition tableaccommodated in the ATM exchange of the third embodiment;

FIG. 18 is a block diagram of a waiting time management tableaccommodated in the ATM exchange of the third embodiment;

FIG. 19 is a flow chart depicting a camp-on request registrationprocedure performed by the ATM exchange of the third embodiment;

FIG. 20 is a flow chart depicting a registration rank change procedureperformed by the ATM exchange of the third embodiment;

FIG. 21 is a sequence diagram for terminals and the ATM exchange of thethird embodiment;

FIG. 22 is a block diagram depicting the structure of the ATM exchangepertaining to a fourth embodiment of the present invention;

FIG. 23 is a flow chart depicting a connection request acceptanceprocedure performed by the ATM exchange of the fourth embodiment;

FIG. 24 is a sequence diagram for terminals and the ATM exchange of thefourth embodiment;

FIG. 25 is a block diagram depicting the structure of the ATM exchangepertaining to a fifth embodiment of the present invention;

FIG. 26 is a block diagram of a registration number management tableaccommodated in the ATM exchange of the fifth embodiment;

FIG. 27 is a flow chart depicting a connection request acceptanceprocedure performed by the ATM exchange of the fifth embodiment;

FIG. 28 is a flow chart depicting a camp-on request registrationprocedure performed by the ATM exchange of the fifth embodiment;

FIG. 29 is a sequence diagram for terminals and the ATM exchange of thefifth embodiment;

FIG. 30 is a block diagram depicting the structure of the ATM exchangepertaining to a sixth embodiment of the present invention;

FIG. 31 is a block diagram of an empty secured band value tableaccommodated in the ATM exchange of the sixth embodiment;

FIG. 32 is a flow chart depicting a connection request acceptanceprocedure performed by the ATM exchange of the sixth embodiment;

FIG. 33 is a sequence diagram for terminals and the ATM exchange of thesixth embodiment;

FIG. 34 is a block diagram depicting the structure of the ATM exchangepertaining to a seventh embodiment of the present invention;

FIG. 35 is a block diagram of an allocated band value table accommodatedin the ATM exchange of the seventh embodiment;

FIG. 36 is a flow chart depicting a connection request acceptanceprocedure performed by the ATM exchange of the seventh embodiment;

FIG. 37 is a sequence diagram for terminals and the ATM exchange of theseventh embodiment;

FIG. 38 is a block diagram depicting the structure of the ATM exchangepertaining to an eighth embodiment of the present invention;

FIG. 39 is a block diagram of a time-specific allocated band value tableaccommodated in the ATM exchange of the eighth embodiment;

FIG. 40 is a flow chart depicting a connection request acceptanceprocedure performed by the ATM exchange of the eighth embodiment;

FIG. 41 is a sequence diagram for terminals and the ATM exchange of theeighth embodiment;

FIG. 42 is a block diagram depicting the structure of the ATM exchangepertaining to a ninth embodiment of the present invention;

FIG. 43 is a block diagram of a time-specific allocated class tableaccommodated in the ATM exchange of the ninth embodiment;

FIG. 44 is a flow chart depicting a connection request acceptanceprocedure performed by the ATM exchange of the ninth embodiment;

FIG. 45 is a sequence diagram for terminals and the ATM exchange of theninth embodiment;

FIG. 46 is a block diagram depicting the structure of the ATM exchangepertaining to a tenth embodiment of the present invention;

FIG. 47 is a block diagram of an ID-specific allocated class tableaccommodated in the ATM exchange of the tenth embodiment;

FIG. 48 is a flow chart depicting a connection request acceptanceprocedure performed by the ATM exchange of the tenth embodiment;

FIG. 49 is a sequence diagram for terminals and the ATM exchange of thetenth embodiment; and

FIG. 50 is a block diagram depicting the structure of a conventional ATMexchange.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described in detail with reference todrawings.

First Embodiment

FIG. 1 depicts a schematic structure of the ATM exchange pertaining tothe first embodiment of the present invention. As shown in the figure,the ATM exchange 100 of the first embodiment comprises a switching unit20, a subscriber's line circuit 30, an output buffer 40, a controldevice 200, and a storage device 300 as its main constituent elements.The subscriber's line circuit 30 is connected to terminals T1 throughTn, and the output buffer 40 is connected to a transmission line 50.Although only one output buffer 40 is shown in the figure, an actual ATMexchange 100 is provided with a plurality of output buffers, and, asschematically shown in FIG. 2, a plurality of ATM exchanges 100 can beconnected by a plurality of transmission lines 50, forming acommunications system.

The subscriber's line circuit 30 controls the timing of celltransmission for each terminal. The switching unit identifies celladdresses based on the headers of the cells inputted via thesubscriber's line circuit 30, and presents these cells to the outputbuffer 40 in accordance with their addresses. The output buffer 40temporarily accumulates cells received from a plurality of terminals andsequentially sends out these cells over the transmission line 50.

The storage device 300 is based on semiconductor memory, and it storesdata concerning the operating state or connection environment of the ATMexchange 100. A call management table 301, a routing table 302, a bandmanagement table 303, a camp-on request management table 304, and atemporarily saved band value management table 305 are accommodated inthe storage device 300.

The control device 200 is based on a processor and executes a connectionrequest acceptance procedure, a camp-on request registration procedure,and a band value updating procedure.

Each procedure will now be described in order.

Connection Request Acceptance Procedure

During the connection request acceptance procedure, it is determinedwhether or not a terminal-originated connection request for a call canbe accepted. When a connection request for a call has been received froma terminal, the control device 200 executes the connection requestacceptance procedure by accessing or updating the contents of the callmanagement table 301, the routing table 302, and the band managementtable 303. The structures of these tables will be described before thedetails of the connection request acceptance procedure are elucidated.

FIG. 3 depicts the structure of the call management table 301. The callmanagement table 301 comprises a plurality of storage areas, each ofwhich stores call management data consisting of a calling terminalnumber, a called terminal number, a band value, a calling VPI, a callingVCI, a called VPI, and a called VCI.

FIG. 4 depicts the structure of the routing table 302. The routing table302 is a table that contains interrelations between called terminals andthe routes used to establish communication with these called terminals.As shown in the figure, the storage area whose position corresponds tothe called terminal number in the routing table 302 stores the routenumber of the route used to establish communication with the terminalthat has this called terminal number.

FIG. 5 depicts the structure of the band management table 303. The bandmanagement table 303 is provided with storage areas for storing themaximum possible allotted band value #MAX for each route and the emptyband value #0 (#MAX−combined use band value #1), and data concerning theroute of a route number K are stored in a storage area whose positioncorresponds to the route number K.

In the connection request acceptance procedure, these tables are used inaccordance with the following sequence.

When a connection request for a call is received from a terminal, thecontrol device 200 assigns a call number to this call and writesinformation (called terminal number) about the party to be connected andcall management data that include the required band value in the storagearea whose position corresponds -to the call number in the callmanagement table 301. The route number of the route used for this callis subsequently obtained by reading the contents of the storage areawhose position corresponds to the called terminal number in the routingtable 302.

The control device 200 then obtains the empty band value of the intendedroute by reading the contents of the storage area whose positioncorresponds to the obtained route number in the band management table303. It is then determined whether or not there is acceptance of aconnection request by comparing the magnitude of the empty band valuethus obtained and the magnitude of the band value (required band value)in the call management table.

When the empty band value exceeds the required band value, the controldevice 200 accepts and connects the connection request and reduces bythe required band value the empty band value pertaining to the intendedroute in the band management table 303. Conversely, when the empty bandvalue is lower than the required band value, the control device 200gives a message that connection is denied to the terminal that hasissued the connection request. As schematically shown in FIG. 6, forexample, the control device 200 gives a message that connection isdenied to a terminal T5 that has issued a connection request in a casein which the terminal T5 has requested that a call be connected at aband value #T5 that exceeds the empty band value #0 (equal to#MAX−(#T1+#T2+#T3+#T4)) when terminals T1 through T4 use bands #T1through #T4, respectively.

Camp-on Request Registration Procedure

A camp-on request is a request issued by a terminal that has beennotified of a connection refusal; the control device 200 executes thecamp-on request registration procedure upon receipt of a camp-onrequest.

The structures of the temporarily saved band value management table 305and the camp-on request management table 304 used during the camp-onrequest registration procedure will first be described.

FIG. 7 depicts the structure of the camp-on request management table304. As shown in the figure, the camp-on request management table 304comprises a plurality of storage areas, each capable of storing a singlepiece of camp-on request data. As is also shown in the figure, camp-onrequest data comprises the same data as the call management data.

A prescribed number of storage areas in which the storage area whoseposition corresponds to the route number is the leading area are used tostore camp-on request data concerning the route having this route numberin the camp-on request management table 304. The storage area serving asa leader in a group of storage areas related to a rout is a storage areafor storing camp-on request data in which permission for communicationis initially granted with respect to this route.

FIG. 8 depicts a structure of the temporarily saved band valuemanagement table 305. In the temporarily saved band value managementtable 305, band values (temporarily saved band values) secured forcamp-on requests are stored for each route. As shown in the figure, thetemporarily saved band value management table 305 comprises a pluralityof storage areas for storing temporarily saved band values, and atemporarily saved band value pertaining to a route with the route numberK is stored in a storage area whose position corresponds to the routenumber K.

The operating procedure of the control device 200 performed during theconnection request acceptance procedure will now be described withreference to FIG. 9.

As shown in the figure, during the connection request acceptanceprocedure, the control device 200 first accesses the routing table 302on the basis of the called terminal number contained in the receivedcamp-on request, and the route to be used for this call is specified(step S101). The control device 200 subsequently searches (step S102)for the first (closest to the leading side) empty area in the group ofstorage areas pertaining to the specified route (hereinafter referred toas “the intended route”).

When there is no empty area (step S103; N), the request terminal isnotified (step S108) that camp-on registration cannot be performed, andthe camp-on request registration procedure is completed.

When, however, there is an empty area (step S103; Y), it is determined(step S104) whether or not this empty area is the leading storage area.

As will be described below, camp-on request data are registered (stored)in the first (closest to the leading side) empty area of the group ofstorage areas pertaining to the intended route in the camp-on requestregistration procedure. No other camp-on requests pertaining to theintended route will therefore be registered when the leading storagearea of the group of storage areas pertaining to the intended route isthe empty area of the camp-on request management table 304. In addition,the fact that the empty area is other than the leading storage area willindicate that other camp-on requests have already been registered.

The control device 200 therefore determines that the received camp-onrequest is the first request pertaining to this intended route when theleading storage area pertaining to the intended route is an empty area(step S104; Y), and executes a procedure whereby the corresponding emptyband value is secured for this camp-on request.

Specifically, the control device 200 stores (step S105) the empty bandvalue #0, which pertains to the intended route and which is stored inthe band management table 303, in the temporarily saved band valuemanagement table 305 as a temporarily saved band value pertaining tothis route. The empty band value #0 that pertains to this route and thatis contained in the band management table 303 is subsequentlyzero-cleared (step S106).

The control device 200 then registers (step S107) the call managementdata (camp-on request data) that pertain to the camp-on request and thathave been stored in the call management table 301 in the searched emptyarea of the camp-on request management table 304, completing the camp-onrequest registration procedure.

When the empty area is not the leading area (step S104; N), that is,when a camp-on request from another terminal has already beenregistered, the control device 200 does not perform the steps S105 orS106 and proceeds to the step S107, and the camp-on request thereof isregistered in the searched empty area of the camp-on request managementtable 304.

Band Value Updating Procedure

The band value updating procedure is executed when communication isdisrupted. During the band value updating procedure, the temporarilysaved band value or the empty band value is updated in accordance withthe band value released by the break in communication. In addition,permission to communicate is granted for a camp-on request registeredduring the band value updating procedure.

FIG. 10 depicts the operating flow of the control device 200 during theband value updating procedure. As shown in the figure, whencommunication is disrupted, the control device 200 identifies (stepS201), based on the contents of the call management table 301, thecalled terminal number pertaining to a terminated call. A route(intended route) with an open band is subsequently specified (step S202)by reading the contents of the storage area that corresponds to thecalled terminal number in the routing table 302. The temporarily savedband value pertaining to the intended route in the temporarily savedband value management table 305 is then increased (step S203) by theband value released by the break in communication.

The control device 200 then checks (step S204) whether or not anycamp-on request data are stored in the leading area of the group ofstorage areas pertaining to the intended route in the camp-on requestmanagement table 304. During this step, these camp-on request data areread as well if any camp-on request data have been stored.

When camp-on registration has been performed (step S204; Y), the controldevice 200 compares (step S205) the magnitude of the band value requiredby this camp-on request and the magnitude of the temporarily saved bandvalue obtained by updating the value in the step S203 (or S207), and theband value updating procedure is completed if the temporarily saved bandvalue is lower than the required band value (step S206; N).

In addition, when the temporarily saved band value exceeds the requiredband value (step S206; Y), the temporarily saved band value is reduced(step S207) by the required band value, and a message is given (stepS208) that calling is possible from the terminal that has issued thiscamp-on request.

The control device 200 then performs (step S209) an ascending procedurefor the camp-on request data pertaining to the intended route in thecamp-on request management table 304. Specifically, the control device200 clears the contents of the leading storage area and copies thecontents of the second and subsequent storage areas to the leadingstorage area in an amount corresponding to one storage area.

The operation returns to the step S204 in order to determine whether theremaining camp-on requests pertaining to the intended route can beprocessed using the temporarily saved band value updated in the stepS207.

When the check in the step S207 has indicated (step S205; N) that theleading area is an empty area, the control device 200 increases (stepS210) the empty band value pertaining to the intended route in the bandmanagement table 303 by the temporarily saved band value calculated inthe step S203 or S207, and zero-clears (step S211) the temporarily savedband value pertaining to the intended route in the temporarily savedband value management table 305, completing the band value updatingprocedure.

The overall operation of the ATM exchange of the first embodiment aimedat handling camp-on requests will now be described with reference toFIG. 11.

A connection request acceptance procedure is first executed in the ATMexchange when a connection request has been received from a terminal A.The terminal is notified of a refusal to connect when no required bandvalue can be secured, as shown in the figure. The terminal A that hasreceived the refusal to connect issues a camp-on request, and a camp-onrequest registration procedure is executed in the ATM exchange that hasreceived the camp-on request.

When the camp-on request issued by the terminal in this case pertains toa route for which no camp-on request has yet been registered, aprocedure in which the unused band pertaining to this route istemporarily saved for this camp-on request is started in the ATMexchange.

As described with reference to FIG. 10, the empty band value pertainingto the intended route is maintained at a zero level in this ATM exchangeduring the period between the receipt of a camp-on request and thetemporary saving of a band that exceeds the required band value. Theresult is that when a terminal A has issued a camp-on request, andanother terminal (terminal B) then issues a connection request withrespect to the intended route, the ATM exchange gives a message thatthis connection request is denied, as shown in FIG. 11. In addition,upon receipt of the camp-on request from the terminal B, the ATMexchange registers this camp-on request as the next item to be processedin the camp-on request management table 304.

A band value updating procedure is executed in the ATM exchange everytime the communication is disrupted following the registration of acamp-on request from the terminal A. When a temporarily saved band valuehas exceeded the band value required by the camp-on request from theterminal A, permission to communicate is issued for this camp-onrequest.

Thus, with the ATM exchange of the first embodiment, accepting a camp-onrequest excludes acceptance of any other connection request, and all theband values that are subsequently released are secured (temporarilystored) for this camp-on request. Permission for a camp-on request istherefore issued in a short time and irrespective of the magnitude ofthe required band value in a communications system in which the presentATM exchange is used.

Second Embodiment

FIG. 12 depicts a schematic structure of the ATM exchange pertaining toa second embodiment of the present invention.

As is shown in the figure, a terminal-specific class table 306 isaccommodated in addition to the already described various tables in thestorage device 300 of the ATM exchange 100 of the second embodiment.

FIG. 13 depicts the structure of the terminal-specific class table 306.As is shown in the figure, the terminal-specific class table 306 storesinterrelations between terminals and classes, which are the parametersused when the order for registering camp-on requests is established.

In the ATM exchange 100 of the second embodiment, the camp-on requestregistration procedure is executed by accessing the contents of theterminal-specific class table 306. The connection request acceptanceprocedure and the band value updating procedure executed in the ATMexchange of the second embodiment are the same as in the firstembodiment, and their description will therefore be omitted.

FIG. 14 depicts the processing sequence of the camp-on requestregistration procedure executed in the ATM exchange of the secondembodiment. As is shown in the figure, when a camp-on request isreceived from a terminal, a control device 200 accesses a routing table302 on the basis of the called terminal numbers contained in the camp-onrequest table thereof, and selects (step S301) the route to be used forthis request. A search is then performed (step S302) for the first emptyarea that pertains to a prescribed route (intended route) in the camp-onrequest management table 304 accommodated in the storage device 300.

When there is no empty area (step S303; N), the request terminal isnotified (step S314) that camp-on registration cannot be performed, andthe procedure is completed.

When there is an empty area (step S303; Y), the class C_(REQ) of therequest terminal is specified (step S304) by accessing theterminal-specific class table 306. The control device 200 theninitializes (step S305) registration rank data P to “1.” Theregistration rank data P are data for specifying the storage areas inwhich camp-on request data are to be registered; the storage device 300contains storage areas for storing the registration rank data P.

Following the initialization of the registration rank data P, thecontrol device 200 checks (step S306) the contents of the P-th storagearea pertaining to the intended route in a camp-on request managementtable, and when camp-on request data are stored in this storage area(step S307; Y), the terminal (hereinafter referred to as “the intendedterminal”) that has issued this camp-on request is identified (stepS308) based on these camp-on request data. The class C_(T) of theintended terminal is subsequently identified (step S309) by accessingthe terminal-specific class table 306. The magnitudes of C_(REQ) andC_(T) are subsequently compared, “1” is added (step S311) to theregistration rank data P when C_(REQ) is higher than C_(T) (step S310;N), and the operation returns to the step S306.

When C_(REQ) is lower than C_(T) (step S310; Y), the control device 200reduces by one the number of each of the P-th and subsequent pieces ofcamp-on request data in order to make the P-th storage area into anempty area, and stores the results again (step S312). The receivedcamp-on request data are registered (step S313) in the P-th storage areamade into an empty area, completing the camp-on request registrationprocedure.

In addition, the operation proceeds to the step S313 and the camp-onrequest data are stored in the storage area when checking the contentsof the P-th area during the step S307 indicates that this area is anempty area (step S307; N).

Although this is not shown in the flow chart, the same procedures asthose involved in the steps S105 and S106 in FIG. 9 are executed wheninitial camp-on request data pertaining to the intended route are storedin the leading (P=1) storage area during the step S313. Specifically, aprocedure is performed in which the empty band value of thecorresponding intended route is secured for the received camp-onrequest.

In addition, procedures corresponding to the steps S206 through S209 inFIG. 10 are executed when camp-on request data other than the initialdata pertaining to the intended route are stored in the leading (P=1)storage area. Specifically, when comparison is performed between themagnitude of the required band value of a camp-on request newlyregistered in the leading storage area and the magnitude of thetemporarily saved value pertaining to the intended route in thetemporarily saved band value management table 305, and the required bandvalue is lower, permission to communicate is granted to the terminalthat has issued this camp-on request.

As described above, the present camp-on request registration procedureallows camp-on request data from a terminal having a high assigned classto be stored in a storage area that is closer to the leading side andthat is selected from among a group of storage areas pertaining to theintended route of the camp-on request management table 304.

As schematically shown in FIG. 15, a camp-on request from a terminal Bis therefore registered as the item to be processed first in an ATMexchange when, for example, a camp-on request is received from aterminal A that has been assigned a class L_(A), and a camp-on requestis then received from a terminal B that has been assigned a higher classL_(B) (>L_(A)). The terminal B will therefore start communicating first,irrespective of the fact that it has issued a camp-on request after theterminal A has done so.

In the ATM exchange in question, as in the ATM exchange of the firstembodiment, no more connection requests are accepted following theacceptance of a camp-on request, and the band values that are releasedthereafter are all used for camp-on requests. Permission to call istherefore issued in a short time with respect to a camp-on request in acommunications system in which the ATM exchange in question is used. Inaddition, camp-on requests are processed in the class sequence assignedto the terminals, making it possible to create a communications systemthat can operate in an efficient manner by employing the ATM exchange inquestion.

Third Embodiment

FIG. 16 depicts a schematic structure of the ATM exchange pertaining toa third embodiment of the present invention. The ATM exchange of thethird embodiment is based on the ATM exchange of the second embodiment,and, as shown in the figure, the storage device 300 thereof accommodatesa class change condition table 307 and a waiting time management table308 in addition to the already described various tables 301 through 306.

FIG. 17 depicts the structure of the class change condition table 307.The class change waiting time and the post-change class are stored foreach terminal in the class change condition table 307, as shown in thefigure.

FIG. 18 depicts the structure of the waiting time management table 308.As shown in the figure, the waiting time management table 308 comprisesa plurality of storage areas, each capable of storing a single piece ofwaiting time management data. The waiting time management data comprisescalling terminal numbers, class change waiting times, and post-changeclasses. A prescribed number of storage areas, among which the storagearea whose position corresponds to the route number is used as a leadingstorage area, are used to store the waiting time management datapertaining to the route having this route number in the waiting timemanagement table 308.

A control device 200 executes a connection request acceptance procedure,a camp-on request registration procedure, a band value updatingprocedure, and a registration rank change procedure. Of theseprocedures, the connection request acceptance procedure and the bandvalue updating procedure are the same as the procedures performed in theATM exchange of the first embodiment.

The details of the camp-on request registration procedure andregistration rank change procedure will now be described.

Camp-on Request Registration Procedure

FIG. 19 depicts the processing sequence of the camp-on requestregistration procedure executed in the ATM exchange of the thirdembodiment. As is shown in the figure, steps S401 through S414 are thesame as the steps S301 through 314 of the camp-on request registrationprocedure (FIG. 14) executed in the ATM exchange of the thirdembodiment, so the description of these steps will be omitted.

In the camp-on request registration procedure executed in the ATMexchange of the third embodiment, camp-on request data are written (stepS413) in a camp-on request management table 304, and the post-changeclass and the class change waiting time pertaining to the requestterminal are then read from the class change condition table 307 andwritten (step S414) in the waiting time management table 308 togetherwith the terminal number (calling terminal number) of the terminal thathas issued a camp-on request.

Registration Rank Change Procedure

The registration rank change procedure, which is a 10 procedure forrearranging the camp-on request data in the camp-on request managementtable 304, is performed every time a prescribed period DT has elapsed.

FIG. 20 depicts the operating sequence of the control device 200 duringthe registration rank change procedure. When the registration rankchange procedure is started, the control device 200 first initializes(step S501) both the route number data P_(p) and the terminal numberdata P_(T) to “1,” as shown in the figure. The route number data P_(p)are data for specifying a single route, and the terminal number dataP_(T) are data for specifying a single terminal. Each type of data isstored in a predetermined storage area in the storage device 300.

Following the initialization of each type of data, the control device200 reads (step S502), from the waiting time management table 308, thepost-change class C_(NEW) and the class change waiting time T pertainingto P_(T)-th terminal of P_(P)-th route.

If the read time T is not “0” (step S503; N), the control device 200stores anew (step S504) the value obtained by subtracting DT from T intothe waiting time management table 308 as a new class change waiting timeT. The calculation result T obtained during this step is subsequentlycompared with “0,” and when T is “0” (step S505; Y), the camp-on requestdata pertaining to P_(T)-th terminal in the camp-on request managementtable 304 are saved (step S506) in the temporary storage area containedin the storage device 300.

A single piece of data subsequent to these camp-on request data is thenstored anew (step S507) in the leading storage area, the stored camp-onrequest data are handled as camp-on request data from a class C_(NEW)terminal, and a camp-on request registration procedure is executed (stepS508). During the step S508, the step S415 is removed from the camp-onrequest registration procedure shown in FIG. 19, whereas during the stepS410 a procedure using C_(NEW) instead of C_(REQ) is executed.

The control device 200 determines whether or not processing has beencompleted for all the terminals. If it has not (step S509; N), then “1”is added (step S510) to terminal number data P_(T), and the operationreturns to the step S502. If processing has been completed for all theterminals (step S509; Y), it is determined whether or not processing hasbeen completed for all the routes. If processing has not been completedfor all the routes (step S511; N), “1” is added to route number dataP_(P) and “1” is set to the terminal number data P_(T) (step S512), andthe operation returns to the step S502.

In addition, if the time T is “0” during the step S503, the class hasalready been changed, so the control device 200 proceeds to the stepS509, and the processing of the next portion of data is started. Inaddition, if the time T is “0” during the step S505, the designated timehas not yet elapsed, so the control device 200 proceeds to the stepS509, and the processing of the next portion of data is started.

The registration rank updating procedure is accomplished when thecontrol device 200 has finished (step S511; Y) processing all theroutes.

Thus, in the registration rank change procedure, the class changewaiting times T that have been copied to the waiting time managementtable 308 are reduced in DT increments, and when T becomes “0,” theregistration rank of the corresponding camp-on request data is changedin accordance with the post-change class of the terminal that has issuedthe request.

The overall processing sequence involving a camp-on request of the ATMexchange of the third embodiment will now be described with reference toa specific example.

A case will be considered in which immediately after (within twominutes) a camp-on request for a certain route has been received for thefirst time from a first terminal for which a class of one, a classchange waiting time of two minutes, and a post-change class of four arespecified, a camp-on request is obtained for the same route from asecond terminal for which a class of three, a class change waiting timeof five minutes, and a post-change class of five are specified.

In this case, in the camp-on request registration procedure executedwhen a camp-on request has been received from the second terminal (FIG.19), the class of the second terminal is higher than the class of thefirst terminal, so steps S412, S413, and S415 are executed at a stage inwhich P=1. As a result, the camp-on request data pertaining to thesecond terminal are stored in the leading storage area pertaining to theintended route of the camp-on request management table 305, and thecamp-on request received from the first terminal is stored in the nextstorage area.

Furthermore, in the ATM exchange of the third embodiment, theregistration rank change procedure is repeated every DT, and in realitythe registration rank of a camp-on request is changed two minutes afterthe camp-on request has been received from the first terminal. Untilthis time, therefore, the camp-on request data pertaining to the secondterminal remain stored in the leading storage area in the camp-onrequest management table 304.

Therefore, as schematically shown in FIG. 21A, permission to communicateis granted with respect to a camp-on request from the second terminalwhen a temporarily saved band value sufficient for responding to thecamp-on request from the second terminal is secured before two minuteshave elapsed.

On the other hand, if a temporarily saved band value sufficient forresponding to a camp-on request from the second terminal is not securedafter two minutes have elapsed following receipt of a camp-on requestfrom the first terminal, steps S506 through S508 involving aregistration rank change procedure will be executed for the firstterminal when two minutes have elapsed. Because at this time thepost-change class of the first terminal is “4,” which is higher than theclass (“3”) of the second terminal, the camp-on request data pertainingto the first terminal and the camp-on request data pertaining to thesecond terminal are transposed in storage areas.

Therefore, as schematically shown in FIG. 21B, it is the first terminalfor which permission to communicate is granted by the band valueupdating procedure executed following this transposition.

Thus, in the ATM exchange of the third embodiment, the processing order(registration rank) of a camp-on request can be changed when aprescribed time has elapsed following the acceptance of the camp-onrequest, making it possible to efficiently deal with camp-on requestsreceived from terminals by setting data that correspond to the usagefrequency or intended use of each terminal in the terminal-specificclass table 306 and the class change condition table 307.

Fourth Embodiment

FIG. 22 depicts the structure of the ATM exchange of a fourthembodiment. The ATM exchange of the fourth embodiment is based on theATM exchange of the first embodiment, and the tables used during itsoperation are the same as in the ATM exchange of the first embodiment.

Unlike in the ATM exchange of the first embodiment, where a camp-onrequest is registered by a camp-on request from a terminal, the ATMexchange of the fourth embodiment automatically registers a camp-onrequest during the connection request acceptance procedure.

FIG. 23 depicts the processing sequence of the connection requestacceptance procedure executed in the ATM exchange of the fourthembodiment. As shown in the figure, a control device 200 first specifies(step S601) the route on the basis of the called terminal number when aconnection request for a call is received from a terminal. The emptyband value #0 pertaining to the intended route is subsequently read froma band management table 303, and the value thereof is compared (stepS602) with the required band value #T.

When the empty band value #0 exceeds the required band value #T (stepS603; Y), a connection procedure is executed (step S604), completing theconnection request acceptance procedure. When the empty band value #0 islower than the required band value #T (step S603; N), the connectionrequest is registered (step S605) as a camp-on request, and the callingterminal,is notified (step S606) that a camp-on request has beenregistered. When registration is performed during the step S605, thesame procedure is executed as the camp-on request registration procedureperformed in the ATM exchange of the first embodiment.

Specifically, a connection request is automatically registered as acamp-on request, and a terminal is notified of this fact, when there isno adequate empty band upon receipt of the connection request from theterminal by the ATM exchange of the fourth embodiment, as schematicallyshown in FIG. 24. The band value updating procedure is repeated everytime connection is broken, and the terminal is notified of permission tocall when a temporarily saved band value exceeding the required bandvalue of the automatically registered camp-on request is obtained.

Fifth Embodiment

FIG. 25 depicts a schematic structure of the ATM exchange pertaining toa fifth embodiment of the present invention. The ATM exchange of thefifth embodiment is based on the ATM exchange of the first embodiment,and the storage device 300 thereof accommodates a registration countmanagement table 309 in addition to the various tables 301 through 305described above.

FIG. 26 depicts the structure of the registration count management table309. As shown in the figure, the registration count management table 309is a table for storing the registration count of camp-on requests foreach route. In the registration count management table 309, theregistration count of camp-on requests for a certain route is stored inthe storage area whose position corresponds to the route number of thisroute.

FIG. 27 depicts the processing sequence of the connection requestacceptance procedure executed in the ATM exchange of the fifthembodiment. As shown in the figure, a control device 200 first specifies(step S701) the route on the basis of the called terminal number when aconnection request for a call is received from a terminal. The emptyband value #0 of the intended route is subsequently read from a bandmanagement table 303, and the value thereof is compared (step S702) withthe required band value #T.

When the result is that the empty band value #0 exceeds the requiredband value #T (step S703; Y), the control device 200 executes (stepS705) a connection procedure, completing the connection requestacceptance procedure. When, however, the empty band value #0 is lowerthan the required band value #T (step S703; N), the registration countof camp-on requests pertaining to the intended route is determined byaccessing the contents of the registration count management table 309,and the terminal is notified (step S704) of the registration count ofthe camp-on requests thus determined.

The camp-on request registration procedure and the band value updatingprocedure have essentially the same sequences as in the firstembodiment, and a detailed discussion will therefore be omitted. In eachof these procedures, the contents of the registration count managementtable 309 are updated when a camp-on request is registered or whenpermission to call has been granted with respect to a camp-on request.

For example, during the camp-on request registration procedure, theregistration of camp-on requests correlated with routes (steps S801 andS802) is followed by the execution of a procedure (step S803) for adding“1” to the registration count of the camp-on requests pertaining tothese routes in the registration count management table 309, as shown inFIG. 28.

Specifically, when the ATM exchange of the fifth embodiment cannotaccept a connection request, the terminal is notified of theregistration count of camp-on requests, as schematically shown in FIG.29. Each of the terminals connected to the ATM exchange in question cantherefore determine whether or not to make a camp-on request, using theregistration count of the indicated camp-on requests.

Sixth Embodiment

FIG. 30 depicts a schematic structure of the ATM exchange pertaining toa sixth embodiment of the present invention. The ATM exchange of thesixth embodiment is based on the ATM exchange of the second embodiment,and the storage device 300 thereof further accommodates an empty securedband value table 310.

FIG. 31 depicts the empty secured band value table 310. As shown in thefigure, empty secured band values for the corresponding classes used ina terminal-specific class table 306 are stored in the empty secured bandvalue table 310. The empty secured band values in the empty secured bandvalue table 310 are used when it is determined whether or not aconnection request or camp-on request from a terminal with acorresponding class can be accepted.

FIG. 32 depicts the processing sequence of the connection requestacceptance procedure executed in the ATM exchange of the sixthembodiment. As shown in the figure, when a connection request isreceived from a terminal, a control device 200 first reads (step S901)the class allocated to the calling terminal from the terminal-specificclass table 306, and reads (step S902) the empty secured band value#T_(RSV) pertaining to this class from the empty secured band valuetable 310. A route based on the called terminal number is subsequentlyselected (step S903). The empty band value #0 of the intended route isread from a band management table 303, and the value thereof is compared(step S904) with the sum of the required band value #T and the emptysecured band value #T_(RSV).

When the result is that the empty band value #0 exceeds the sum of therequired band value #T and the empty secured band value #T_(RSV) (stepS905; Y), the control device 200 executes (step S907) a connectionprocedure, completing the connection request acceptance procedure. When,however, the empty band value #0 is lower than the sum of the requiredband value #T and the empty secured band value #T_(RSV) (step S905; N),the calling terminal is notified (step S906) of a refusal to connect,completing the connection request acceptance procedure.

The band value updating procedure performed by the ATM exchange of thesixth embodiment is the same as the band value updating procedure in thesecond embodiment. In addition, the camp-on request registrationprocedure performed by the ATM exchange of the sixth embodiment isvirtually the same as the camp-on request registration procedure in thesecond embodiment. In the camp-on request registration procedureperformed in the sixth embodiment, however, temporary saving is startedwhile the empty band value is retained in an amount corresponding to theempty secured band value when the first camp-on request pertaining to acertain route has been received. Specifically, a band value obtained byreducing the corresponding empty band value by an empty secured bandvalue is stored as the temporarily saved band value pertaining to theintended route in a temporarily saved band value management table 305,and the empty secured band value is stored as an empty band value in theband management table 303.

Thus, when a camp-on request for a certain route is made by a certainterminal in the ATM exchange of the sixth embodiment, an empty bandvalue adjusted by the empty secured band value pertaining to the classof this terminal is secured as the empty band value pertaining to thisroute.

Therefore, even when a camp-on request from a terminal A has beenregistered, as schematically shown in FIG. 33, connection requests froma terminal B are sometimes accepted with respect to the same route asthat for which the camp-on request has been issued. Specifically, aconnection request from a terminal B is accepted and connection-madewhen the empty secured band value pertaining to the terminal B is lowerthan the empty secured band value pertaining to the terminal A, and theband value necessary for the connection request made by the terminal Bis lower than the difference between the two empty secured band values.

Seventh Embodiment

FIG. 34 depicts a schematic structure of the ATM exchange pertaining toa seventh embodiment of the present invention. The ATM exchange of theseventh embodiment is based on the ATM exchange of the secondembodiment, and the storage device 300 thereof further accommodates anallocated band value table 311.

FIG. 35 depicts the structure of the allocated band value table 311. Asshown in the figure, allocated band values for the corresponding classesused in a terminal-specific class table 306 are stored in the allocatedband value table 311.

FIG. 36 depicts the processing sequence of the connection requestacceptance procedure executed in the ATM exchange of the seventhembodiment. As shown in the figure, when a connection request isreceived from a terminal, a control device 200 first reads (step S1001)the class allocated to the calling terminal from the terminal-specificclass table 306, and reads (step S1002) the allocated band value #Wpertaining to this class from the allocated band value table 311. Aroute based on the called terminal number is subsequently selected (stepS1003). The magnitude of the allocated band value #W and the magnitudeof the required band value #T are subsequently compared with each other(step S1003), and when the allocated band value #W is higher than therequired band value #T (step S1004; Y), a connection procedure isexecuted (step S1005), completing the connection request acceptanceprocedure. When the allocated band value. #W is lower than the requiredband value #T (step S1005; N), the calling terminal is notified (stepS1006) that connection is impossible, completing the connection requestacceptance procedure.

The band value updating procedure performed by the ATM exchange of theseventh embodiment is the same as the band value updating procedure inthe second embodiment. In addition, the camp-on request registrationprocedure performed by the ATM exchange of the seventh embodiment isvirtually the same as the camp-on request registration procedure in thesecond embodiment. In the camp-on request registration procedureperformed in the seventh embodiment, however, the magnitude of theallocated band value #W and the magnitude of the required band value #Tare compared with each other when a camp-on request has been received,and a message is given that the camp-on request cannot be registeredwhen the allocated band value #W is lower than the required band value#T.

Specifically, a terminal having a certain class is notified of a refusalto connect or register when this terminal makes a connection request ora camp-on request requiring a band that exceeds the allocated band valuepertaining to this class in the ATM exchange of the seventh embodiment,as schematically shown in FIG. 37.

Eighth Embodiment

FIG. 38 depicts a schematic structure of the ATM exchange of an eighthembodiment of the present invention. The ATM exchange of the eighthembodiment is based on the ATM exchange of the seventh embodiment; atime-specific allocated band value table 312 is stored instead of theallocated band value table 311 in the storage device 300 thereof. TheATM exchange 100 also has a clock 60 for outputting the current time.

FIG. 39 shows the structure of the time-specific allocated band valuetable. As shown in the figure, the time-specific allocated band valuetable 312 classifies by the time period and stores allocated band valueswith respect to the corresponding classes used in the terminal-specificclass table 306.

FIG. 40 depicts the processing sequence of the connection requestacceptance procedure executed in the ATM exchange of the eighthembodiment. As shown in the figure, when a connection request isreceived from a terminal, a control device 200 first reads (step S1101)the class allocated to the calling terminal from the terminal-specificclass table 306. In addition, the current time is obtained (step S1102)from the clock 60, and the allocated band value #W_(T) that exists atthe current time and that pertains to this class is read (step S1103)from the time-specific allocated band value table 312. The magnitude ofthe allocated band value #W_(T) and the magnitude of the required bandvalue #T are subsequently compared with each other (step S1104), andwhen the allocated band value #W_(T) is higher than the required bandvalue #T (step S1105; Y), a connection procedure is executed (stepS1107), completing the connection request acceptance procedure. When theallocated band value #W_(T) is lower than the required band value #T(step S1105; N), the calling terminal is notified (step S1106) thatconnection is impossible, completing the connection request acceptanceprocedure.

In the camp-on request registration procedure performed in the eighthembodiment, the magnitude of the allocated band value #W_(T) and themagnitude of the required band value #T are compared with each otherwhen a camp-on request has been received, and a message is given thatthe camp-on request cannot be registered when the allocated band value#W_(T) is lower than the required band value #T.

Specifically, when, as schematically shown in FIG. 41, a connectionrequest or a camp-on request has been received from a terminal having acertain class in the ATM exchange of the eighth embodiment, it isdetermined that the connection request cannot be accepted or the camp-onrequest registered, depending on the time period in which this requesthas been issued.

Ninth Embodiment

FIG. 42 depicts a schematic structure of the ATM exchange pertaining toa ninth embodiment of the present invention. The ATM exchange of theninth embodiment is based on the ATM exchange of the eighth embodiment,and a time-specific class table 313 and an allocated band value table311 (FIG. 35) are stored in the storage device 300 thereof instead ofthe terminal-specific class table 306 and the time-specific allocatedband value table 312.

FIG. 43 depicts the structure of the time-specific class table 313. Asshown in the figure, terminal classes are stored for different periodsof time in the time-specific class table 313.

FIG. 44 depicts the processing sequence of the connection requestacceptance procedure executed in the ATM exchange of the ninthembodiment. As shown in the figure, a control device 200 first obtains(step S1201) the current time from a clock 60 when a connection requesthas been received from a terminal. The class pertaining to the callingterminal at the current time is subsequently read (step S1202) from thetime-specific class table 313. In addition, the allocated band value#W_(C) pertaining to this class is read (step S1203) from the allocatedband value table 311.

The magnitude of the allocated band value #W_(C) that has been read andthe magnitude of a required band value #T are subsequently compared witheach other (step S1204), and when the allocated band value #W_(C) ishigher than the required band value #T (step S1205; Y), a connectionprocedure is executed (step S1207), completing the connection requestacceptance procedure. When the allocated band value #W_(c) is lower thanthe required band value #T (step S1205; N), the calling terminal isnotified (step S1206) that connection is impossible, completing theconnection request acceptance procedure.

In the camp-on request registration procedure performed in the ninthembodiment, an allocated band value #W_(C) is selected as a result ofthe same procedure when a camp-on request is received, and the requestterminal is notified that the camp-on request cannot be registered whenthe allocated band value #W_(c) is lower than the required band value#T. When the allocated band value #W_(C) is higher than the requiredband value #T, a registration position is established for the camp-onrequest using the class that has been read in the process of selectingthe allocated band value #W_(C).

Thus, in the ATM exchange of the ninth embodiment, classes are allocatedto terminals for each time period, and the registration ranks of camp-onrequests are established using these classes. This allows camp-onrequests from the terminals to be handled efficiently.

In addition, when, as schematically shown in FIG. 45, a connectionrequest or a camp-on request has been received from a certain terminalin the ATM exchange of the ninth embodiment, it is determined that theconnection request cannot be accepted or the camp-on request registered,depending on the time period in which this request has been issued.

Tenth Embodiment

FIG. 46 depicts a schematic structure of the ATM exchange pertaining toa tenth embodiment of the present invention. The ATM exchange of thetenth embodiment is a modification of the ATM exchange of the seventhembodiment, and a caller-specific class table 314 is stored in thestorage device 300 instead of the terminal-specific class table 306.

FIG. 47 depicts the structure of the caller-specific class table 314. Asshown in the figure, classes assigned to callers are stored in thecaller-specific class table 314 in correlation with the identifyinginformation (ID) of each caller (terminal user).

The ATM exchange of the tenth embodiment operates upon receipt of anID-containing connection request or camp-on request.

FIG. 48 depicts the processing sequence of the connection requestacceptance procedure executed in the ATM exchange of the tenthembodiment. As shown in the figure, when a connection request isreceived, a control device 200 first samples (step S1301) from theconnection request. The class associated with the sampled ID is thenread (step S1302) from the caller-specific class table 314. Theallocated band value #W pertaining to this class is subsequently read(step S1303) from the allocated band value table 311, and the magnitudeof the allocated band value #W and the magnitude of the required bandvalue #T are subsequently compared with each other (step S1304).

When the allocated band value #W is higher than the required band value#T (step S1305; Y), a connection procedure is executed (step S1307),completing the connection request acceptance procedure. When theallocated band value #W is lower than the required band value #T (stepS1305; N), the request terminal is notified (step S1306) that connectionis impossible, completing the connection request acceptance procedure.

In the camp-on request registration procedure performed in the tenthembodiment, an allocated band value #W is selected as a result of thesame procedure when a camp-on request is received, and the requestterminal is notified that the camp-on request cannot be registered whenthe allocated band value #W is lower than the required band value #T.When the allocated band value #W is higher than the required band value#T, a registration position is established for the camp-on request usingthe class that has been read in the process of selecting the allocatedband value #W.

Thus, in the ATM exchange of the tenth embodiment, the registrationranks of camp-on requests are established using classes allocated tocallers.

In addition, when, as schematically shown in FIG. 49, a connectionrequest or a camp-on request that requires a band higher than theallocated band value pertaining to a certain class has been receivedfrom a terminal that has been assigned this class in the ATM exchange ofthe tenth embodiment, this terminal is notified of a refusal to connector register.

Modified Embodiments

The ATM exchange of each embodiment can be modified in a variety ofways. For example, providing a time-specific class table instead of theterminal-specific class table of the ATM exchange of the secondembodiment should allocate classes to different terminals in accordancewith periods of time, and establish the registration ranks of camp-onrequests on the basis of the classes associated with these periods oftime. It is also possible to establish the registration ranks of camp-onrequests in accordance with the callers by providing a caller-specificclass table instead of the terminal-specific class table of the ATMexchange of the second embodiment.

Another alternative is to use one table to control both the empty bandvalues and the temporarily saved band values instead of using a bandmanagement table and a temporarily saved band value management table.

What is claimed is:
 1. A switching system for registering a camp-on whenan empty band value corresponding to a band value requested from atransmitting terminal cannot be reserved, said switching systemcomprising: storage means for storing a band value requested from atransmitting terminal for which a camp-on is registered; temporarilysaved band value management means for adding an empty band valuereleased by a disconnected call to a temporarily saved band value whichis reserved for the transmitting terminal; and camp-on execution meansfor executing the camp-on when the temporarily saved band valuesatisfying the band value stored in said storage means is gotten for thetransmitting terminal by said temporarily saved band value managementmeans.
 2. A switching system for registering a camp-on when an emptyband value corresponding to a band value requested from a transmittingterminal cannot be reserved, said switching system comprising: bandmanagement process means for managing an empty band value and a usedband value on a transmission line; camp-on registration process meansfor accepting a camp-on request from a transmitting terminal and forregistering a camp-on for the transmitting terminal; temporarily savedband value management means, when said band management process meansdetects an empty band value released by a disconnected call for addingthe empty band to a temporarily saved band value which is reserved forthe transmitting terminal for which the camp-on is registered as a partof the used band value, and camp-on execution means for executing thecamp-on when the temporarily saved band value satisfies the band valuerequested from the transmitting terminal.
 3. A switching system forregistering a camp-on when an empty band value corresponding to a bandrequested from a transmitting terminal cannot be reserved, saidswitching system comprising: band management process means for managingan empty band value and a used band value on a transmission line;camp-on registration process registration means for distinguishing aclass allocated for a transmitting terminal for which a camp-on isregistered and for registering the camp-on for the transmitting terminalassociating with the class; temporarily saved band value managementmeans, when said band management process means detects an empty bandvalue released by a disconnected call for adding the empty band to atemporarily saved band value which is reserved for the transmittingterminal associating with the class of a higher priority among thetransmitting terminals for which the camp-ons are registered as a usedband value, and camp-on execution means for executing the camp-on whenthe temporarily saved band value satisfies the band value requested fromthe transmitting terminal.
 4. A switching system according to claim 1 orclaim 2 or claim 3, further comprising: notification means for notifyingthat the camp-on is executable to the transmitting terminal.
 5. Aswitching system comprising: band management process means for managingan empty band value and a used band value on a transmission line;camp-on registration process means, for registering a camp-on for thetransmitting terminal when an empty band value corresponding to a bandvalue requested from a transmitting terminal cannot be reserved; andnotification means for notifying the transmitting terminal ofregistration of the camp-on when said camp-on registration process meansregisters the camp-on; wherein the switching system further comprises:temporarily saved band value management means, when said band managementprocess means detects an empty band value released by a disconnectedcall, for adding the empty band to a temporarily saved band value whichis reserved form the transmitting terminal by which the camp-on isregistered; and second notification means for notifying the transmittingterminal that the camp-on is executable when the band value requiredfrom the transmitting terminal is gotten.